An example of a known offset printing machine capable of printing on both sides of a printing sheet, as shown in FIG. 1, includes an outside plate cylinder a and an outside rubber cylinder b for printing the outside of a printing sheet and an impression cylinder c serving also as an inside rubber cylinder and an inside plate cylinder d. A packing sheet (not shown in FIG. 1) is laid over the impression cylinder c. A printing sheet f is fed from a printing sheet feeding stand e to the impression cylinder c where it is clamped after which both sides of the printing sheet are printed. After being printed, the printing sheet is released and delivered to a printing sheet discharging stand g. In this manner, one printing cycle is accomplished.
The invention relates to a packing sheet overlaying device for laying a packing sheet over the impression cylinder of the above-described printing machine, the impression cylinder for a numbering machine, or the like. An object of the invention is to provide a packing sheet overlaying device with which a packing sheet can be readily and quickly laid over the cylinder of a printing machine and in which the packing sheet can be frequently replaced and printing sheets can be satisfactorily clamped.